Pick the right place. Best winter rivers are Colorado tailwaters like the South Platte, Yampa, Frying Pan, or Gunnison; Montana tailwaters like the Bighorn and Madison; Wyoming rivers like the Snake River in Jackson; Idaho tailwaters like the South Fork and Henry’s Fork of the Snake; the Provo and Green in Utah, Great Lakes tributaries, and the upper Sacramento in California. As you can see, a fishing trip can often be combined with a ski trip.
Slow and deep is best. Use a strike indicator and weighted fly, or weight on the leader and the high-stick method, which keeps most of your fly line off the water. Dead drift is critical in winter because trout won’t chase a fly in cold water.
Although dead-drift nymphing is best, if you prefer to swing a fly for trout or steelhead, use a sinking tip line with a very strong mend at the beginning of the cast so your fly swings slow and deep.
Occasionally trout will rise during the winter, almost always to small midges or olive mayflies. A small midge emerger or a tiny olive mayfly emerger will be the only dries you’ll need to carry.
You’ll see the most surface activity mid-afternoon on sunny days, or, surprisingly, all day long on gray snowy days without wind.
Light tippets are usually more productive in winter. The flies are small and water is clear. I use 6X Mirage for trout fishing and 4X Mirage for steelhead under most conditions.
Fish tend to “pod up” in winter in deeper, slower water. Once you catch one try not to disturb the water and continue to fish in the same place. Fish the slow water thoroughly, but move often if you aren’t connecting